Hold the soap!

Another case of "everything you know is wrong" -- though to be fair, who knew about DNA way back when, and more recently, who suspected that ancient DNA would be recoverable?

Washing, brushing and varnishing fossils — all standard conservation treatments used by many fossil hunters and museum curators alike — vastly reduces the chances of recovering ancient DNA.

Instead, excavators should be handling at least some of their bounty with gloves, and freezing samples as they are found, dirt and all, concludes a paper in the Proceedings of the National Academy of Sciences today . . .

Geigl and her colleagues looked at 3,200-year-old fossil bones belonging to a single individual of an extinct cattle species, called an aurochs. The fossils were dug up at a site in France at two different times — either in 1947, and stored in a museum collection, or in 2004, and conserved in sterile conditions at -20 ºC.

The team's attempts to extract DNA from the 1947 bones all failed. The newly excavated fossils, however, all yielded DNA.

Because the bones had been buried for the same amount of time, and in the same conditions, the conservation method had to be to blame says Geigl. "As much DNA was degraded in these 57 years as in the 3,200 years before," she says.

Posted by David on January 10, 2007 2:44 PM